Effect of drying methods and pre-treatments on bioactive potential of persimmon ( diospyros kaki l.)

Abstract

In this research, persimmon samples (sliced, pureed) were dehydrated by convective (50 and 100 degrees C) and microwave (100 W) drying techniques with different pre-treatment combinations of sugar addition (25%) and blanching (100 degrees C, 5 min). Each pre-treatment consisting of sugar addition, slicing, and blanching resulted in a significant increase in color parameters compared to unpretreated samples. Color parameters measured at low drying temperatures were lower than high ones. Also, 100 W dried samples were higher in total anthocyanin content, and the pureed samples were 24.80% higher than sliced ones. The bioactive potential was evaluated regarding extractable, hydrolysable, and bioaccessible phenolic fractions by total phenolic content and ABTS (2,2 '-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl) and CUPRAC (Cupric Reducing Antioxidant Capacity) antioxidant capacity assays. (i) 50 degrees C drying prevailed on drying at 100 degrees C and 100 W, especially in terms of extractable phenolic fractions and bioaccessible phenolic fractions; (ii) Sliced samples were higher for EPF and BPF, while pureed ones were higher in hydrolysable phenolic fractions; (iii) Blanched samples were relatively higher than unblanched ones in total phenolic content. For antioxidant capacity assays, extractable phenolic fractions were higher in blanched samples and bioaccessible phenolic fractions in unblanched ones (TEAC(ABTS), TEAC(CUPRAC)). (iv) Sugar addition negatively affected the bioactive potential in persimmon samples; no-sugar-added samples were higher, especially in bioaccessible phenolic fractions (p < 0.01; Total phenolic content, TEAC(ABTS,) TEAC(CUPRAC)). (v) The CUPRAC assay was the most appropriate method due to providing a view of more statistical distinction by picturing the same potential.